1. Field of Invention
The invention relates in general to the indicator positioning technology, and more particularly to a method for calibrating coordinates of a touch screen.
2. Brief Discussion of the Related Art
Recently, the technology is rapidly developed. A handheld device, such as a smart mobile phone, a personal digital assistant (PDA), a global positioning system (GPS), or the like, has become more and more popularized. The above-mentioned devices have touch screens, so the calibrating technology between a touch sensor and a display device become very important. In the past, a resistive touch sensor is usually used. The resistive sensor has to sense the coordinates of indicators on the screen by way of pressure sensing. A liquid crystal display is usually used in the handheld device and the resistive sensor also has to overlap with the liquid crystal display. Thus, when the resistive sensor is pressed, the liquid crystal display is also pressed. After a long period of time, the liquid crystal display may be damaged. In addition, the resolution of the resistive sensor is lower, and the condition of the unprecise coordinate positioning tends to occur.
In the prior art, a capacitive touch sensor is also used. The capacitive sensor is widely applied to the touch screen of the handheld device. However, when the capacitive sensor is applied to the touch screen, the problem of precision exists due to the mismatch between the coordinate arrangements of the capacitive touch pad and the display.